In-band artifact and noise present a major obstacle to efficient extraction of accurate, reliable, and repeatable information from ambulatory recordings of subcutaneous and surface ECGs. With more than 4 million patients a year experiencing ambulatory evaluations for cardiac arrhythmia, in-band artifact and noise is an urgent, wide-reaching challenge. In clinical care, for example, the high incidence of false positive arrhythmia detections resulting from noise and artifact can require expensive manual over-read, leading to poor operational efficiencies and higher cost of delivering care. Some manufacturers have attempted to address this issue in ambulatory event recorders by tuning the arrhythmia detection algorithm to increase positive predictive value (reduce false positive events) at the expense of decreased sensitivity, resulting in missed events and a reduction in diagnostic yield. In addition to inducing significant numbers of false positive events, noise can mask P-waves, rendering a definitive diagnosis of atrial fibrillation difficult. Noise also impacts studies of drg safety and effectiveness because noise introduces variability in risk markers which, in turn, increases sample size and cost and compromises the quality of information. To address this need, a novel miniature (15 cc) fully functioning Holter/event/mobile cardiac telemetry device will be developed in Phase II. This device employs the patented VivaQuant MDSP algorithm for real- time processing of ECGs. This algorithm provides for >26 dB reduction in in-band noise without distorting ECG morphology and provides superior event detection sensitivity and PPV, especially in noisy recordings. This Phase II effort will build upon a successful Phase I effort an will optimize algorithm power consumption and performance based upon numerical optimization strategies researched in Phase I. The remaining features including wireless communications, data compression, and symptomatic event recording will be implemented and tested in Phase II. At the completion of the Phase II effort, all testing to applicable standards and documentation will be completed and a 510k will be submitted to FDA. The Holter/event recorder developed in this multi-phase effort will result in a significant improvement in the quality of diagnostic information available to physicians, leading to better informed therapeutic decisions, improved patient quality of life, and higher-quality care delivered at a lower cost. The small size and othe patient-friendly features of the device will render it more comfortable to wear, leading to improved patient compliance and higher-quality diagnostic information. In addition, once the embedded algorithm is optimized, we will pursue partnerships to commercialize the MDSP algorithm in other applications where accurate ultra low-power ECG processing is required such as for implantable loop recorders, subcutaneous defibrillators, and neural stimulation devices.